When I first looked at this I thought of Hohenbuehelia, but mostly I like to look at a specimen before calling something this genus. Under the microscope it's a very simple job to see if something is a species of Hohenbuehelia. Mostly I see this genus on the sides or undersides of fallen branches, trunks, etc in sheltered areas and the stemless mushrooms are small (say a centimetre or so). However there is the odd species which does grow in more exposed habitats and is larger. There are not too many genera of stemless mushrooms, in particular in exposed habitats, so I've stuck Hohenbuehelia on this as seeming to be the most plausible of the possibilities, not because I'm sure that's what this is.